Noise reduction for differently exposed images

For scenes under low lighting condition, cameras are usually set to a high sensitivity (ISO) mode to reduce motion blur at the cost of increased image noise. When multiple differently exposed images are used to generate a high dynamic range (HDR) image, the high ISO noise from each low dynamic range (LDR) image can be further amplified by the HDR synthesis algorithm which would result in severely degradation of visual quality. This paper proposes an intensity mapping function based noise reduction method for differently exposed images with high ISO noise. The proposed method does not require any knowledge on either camera response functions or exposure times. In addition, the method is simple yet effective for noise removal from the LDR images without introducing any blurring or other artifacts.